NGC 6981 / C2050-127 / Messier 72 (Updated 2009) RA: 20:53:27.70 DEC: -12:32:14.3 (J2000) ============================================================ Bytes Format Explanation 1-8 A8 Star ID 10-32 A11,1x,A11 Position 34-35 A2 Units for position R0 denotes RA, DEC in the J2000 coordinates R5 denotes RA, DEC in the 1950 coordinates XA denotes X, Y in arcseconds XP denotes X, Y in pixels 37-44 F8.4 Period (days) 46-51 F6.3 Mean magnitude (or maximum magnitude if "max" is indicated in the remarks column) 53-57 F5.3 Light amplitude (range of variability) 59 A1 Colour for mean magnitude and amplitude e.g. B, V, R, I or P (for photographic). 61-65 A5 Type of variable (draft 2006 GCVS classifications) NV denotes not variable 67-80 A19 Notes and Remarks (f denotes field star) "--" or "----" indicates no data available ========================================================================= ID Position Period ampl C Type Notes/ RA/X Dec/Y Units Remarks ========================================================================= 1 43.5 -54 XA 0.6198 16.85 0.80 P RR0 Ros 2 99 194.4 XA 0.4653 17.258 1.660 B RR0 3 -52.5 -58.5 XA 0.4976 17.090 1.583 B RR0 4 -106.5 37.5 XA 0.5525 17.279 1.182 B RR0 5 -38.4 -21.6 XA 0.4991 16.91 1.03 P RR0 Shap 6 78 78.6 XA NV? 7 -3.6 55.5 XA 0.5246 17.118 1.173 B RR0 8 -6.6 89.4 XA 0.5684 17.339 1.009 B RR0 9 11.4 50.4 XA 0.6030 17.219 0.804 B RR0 10 -48.6 -73.5 XA 0.5582 17.303 1.080 B RR0 11 57 -36.6 XA 0.5200 17.351 0.906 B RR0 12 9 -21.6 XA 0.4111 16.74 0.86 P RR0 Shap 13 13.5 17.4 XA 0.5511 16.415 1.074 B RR0 blend 14 -13.5 36.0 XA 0.5904 16.73 0.66 P RR0 Shap;Note 15 -64.5 -21 XA 0.5504 17.224 0.926 B RR0 16 -4.5 -19.5 XA 0.5855 16.824 0.896 B RR0 blend 17 3.6 -43.5 XA 0.5735 17.174 1.048 B RR0 18 -26.4 -37.5 XA 0.5202 15.99 0.58 P RR0 Shap 19 3 112.5 XA NV 20 -54.6 15 XA 0.5950 16.95 0.90 P RR0 Ros 21 -82.5 12.6 XA 0.5312 17.336 1.294 B RR0 22 -113.4 1.5 XA NV 23 -99 116.4 XA 0.5851 17.451 0.778 B RR0 24 -15.6 -24 XA 0.4973 16.38 0.35 P RR0 Shap;Note 25 -133.5 67.5 XA 0.3534 17.181 0.555 B RR1 26 -91.5 -45 XA NV? 27 209.4 -234 XA 0.6738 17.053 1.487 B RR0 f? 28 65.4 81 XA 0.5672 17.303 0.811 B RR0 29 -36 -52.5 XA 0.6055 17.188 0.800 B RR0 Note 30 71.4 -97.5 XA NV? 31 5.4 36.6 XA 0.5325 17.036 0.922 B RR0 blend 32 -138 -42 XA 0.5283 17.369 0.942 B RR0 33 2.4 -60.6 XA NV? Note 34 -6 7.5 XA 16.40 0.67 Shap 35 231 27 XA 0.5438 17.27 0.97 B RR0 36 -12 0 XA 16.4 0.8 P Saw 37 7 -8 XA 16.0 1.0 P Saw 38 5 -9 XA 16.95 0.7 P Saw 39 195 243 XA 17.2 0.8 P Saw 40 18 16 XA 16.9 1.0 P Saw 41 15 -20 XA 17.1 0.8 P Saw;Note 42 12 3 XA SR? red S1 -44 -36.5 XA S2 -15.9 -9.5 XA S3 -10.0 -4.5 XA S4 -0.4 -11.9 XA S5 0.4 2.7 XA S6 5.4 -17.5 XA S7 9.6 -2.4 XA S8 13.6 -9.0 XA S9 24.9 -9.0 XA ======================================================================= Supplementary Notes and References The x,y coordinates listed above for all of the variables are from their "discovery" papers. Periods, magnitudes, amplitudes and comments for V1-41 are from Dickens & Flinn (1972, MNRAS 158, 99) unless indicated Shap or Ros or Saw in the remarks column in which case they are from Shapley & Ritchie (1920, ApJ 52, 232) or from Rosino (1953, Bologna Pub 6, No. 2, p49) or from Sawyer (1953, JRASC 47, 229) NV status for V6, V19, V22, V26, V30, V33 are from Rosino (1953, Bologna Pub 6, No. 2, p49). Armando Arellano Ferro is currently working on a paper on the variables in thsi cluster. He expects to submit it in 2010. Brian Skiff sent C Clement an email in June 2004 with RA and dec (J2000) for some of the variables. ================================================ Notes on individual stars V14: Samus (2009 - private communication) pointed out the the y coordinate for V14 was incorrectly listed in our previous on-line catalogs. y(V14) should be +36.0". V24: The period is uncertain. This star needs further investigation to determine if it actually varies. V29, V33: The sign of the x coordinate was incorrect for these two variables in Sawyer Hogg's three (1939, 1955, 1973) catalogs and this error was repeated in our on-line catalogs. x(V29) should be -36.0" and x(V33) should be -2.4". The correct values were listed by Shapley (1920, ApJ 52, 73) in his discovery paper. The error for V29 was pointed out by Kadla et al (1998, Astron & Astrophys Transactions 15, 137) and the error in V33 was pointed out by Samus (2009 - private communication). V41: Kadla et al (1998, Astron & Astrophys Transactions 15, 137) pointed out that the sign of the x coordinate was incorrect in Sawyer Hogg's (1955, 1973) 2nd and 3rd catlogs. x(V41) should be +15". It appears that the error originated in her discovery paper (Sawyer 1953, JRASC 47, 229). ========================================================== Discovery of the variable stars in M72 V1-34 (V6, V19, V33 were supsected variables) discovered by Ritchie and announced by Shapley (1920, ApJ 52, 73) with x,y coordinates and an ID chart. Kadla et al. (1995, A&A 302, 723) later showed that V6, V19 and V33 are giant branch stars. V35-41 Sawyer (1953, JRASC 47, 229) with x,y coordinates and an ID chart. V35 was later found to be an RR Lyrae variable, but nothing further is known about V36-V41. V42 Dickens & Flinn (1973, IAU Colloq 21, Var Stars in GCs and Related Systems, p82) noted that they had discovered a new red variable near the cluster centre. The number 42 was assigned and x,y coordinates were listed by Sawyer Hogg (1973) in her 3rd catalog, based on unpublished correspondence with Dickens. S1-S9 (and R1-R7 which are not listed in the above table) Kadla et al. (1995, A&A 302, 723) and Kadla et al. (1996, IBVS 4413) with x,y coordinates and ID charts. S1-S9 were classified as suspected variables based on their location in the RR Lyrae instability strip in the CMD. No variations were detected because their study was based on one B frame and one V frame taken simultaneously. Using the same data, Kadla et al. also listed 7 "possible" variables (numbered R1-7) located at the intersection of the instability strip and the red HB. Approximately 33 of variables V1-42 were also labelled on the ID charts in these papers by Kadla et al.